not sure on a diesel but on my k1500 theres one on the top of the intake buy the thermostat housing and one on the side of the block on the drivers side. mine didnt read at all and sometimes would jump wildly. the one on the side of the block was the culprit. one is a temprature sender (top of intake) the other is a temprature switch (side of block) hope this helps.

not sure on a diesel but on my k1500 theres one on the top of the intake buy the thermostat housing and one on the side of the block on the drivers side. mine didnt read at all and sometimes would jump wildly. the one on the side of the block was the culprit. one is a temprature sender (top of intake) the other is a temprature switch (side of block) hope this helps.